# X-Ray Timer > Industrial radiography exposure time calculator for radioactive sources. (iPhone/iPad app by Lance Henderson.) - Source: https://appshunter.io/ios/app/x-ray-timer/id350390647 (this page in markdown: same URL + `.md`) - Developer: [Lance Henderson](https://appshunter.io/developer/348247919) - Category: Utilities - Price: Free - Rating: 4.80/5 from 8 App Store ratings · 62 written reviews indexed - Age rating: 4+ - Requires: iOS 8.0 · 0 MB - Languages: American English - Released: 2010-01-14 - Data updated: 2026-07-17 - Monetization: paid - User reviews in markdown: https://appshunter.io/ios/app/x-ray-timer/id350390647/reviews.md ## What is X? Updated for iOS10. Only Useful for Industrial Radiographers! This is an application to replace the aggravating usage of slide rules to calculate radiography shot times. It is applicable to Industrial Radiographers working with radioactive materials (not x-ray machines). It works with both Iridium and Cobalt sources. This app has been tested in the field with working radiography crews and the response has be great. Just set the number of curies, the thickness of the steel (inches), and the source to film distance (in inches). Hit the calculate button and you will have the exposure time. ## Key features - Calculate radiography shot times - Supports Iridium and Cobalt sources - Input curies, thickness, and distance - Field-tested for accuracy - Replaces slide rule calculations ## Recent user reviews (10 of 62) All indexed reviews: https://appshunter.io/ios/app/x-ray-timer/id350390647/reviews.md ### 4/5 — Question *2025-11-07, version 4.0* Is there anyway you can add a feature where it saves your recent calculations ### 5/5 — Excellent app *2025-03-12, version 4.0* This app is amazing and saves so much time. Would be really cool if there was a memory feature to look up recent calculations while app is still open. ### 5/5 — NDT gamma calculator *2024-10-30, version 4.0* I use this app daily at work. The times are bang on when developing at 68F for 6 minutes. ### 3/5 — Exposures *2024-05-30, version 4.0* The exposures I’ve been getting are abit off graphs are kinda light ok for a test shot tho ### 2/5 — ?? *2021-02-28, version 4.0* it is for how much density 3? ### 5/5 — Prefer this to the JEM calculator *2020-11-11, version 4.0* This app works great. As long as I enter all the numbers in correctly my film turns out. It even works well when I’m calculating for a concrete shot. It stopped working after a recent IOS update. Hoping it gets back up and running soon! ### 5/5 — Great *2017-02-01, version 4.0* This app works very well just like using a slide calculator ### 3/5 — Great for Xray Hands *2016-09-15, version 3.0* Simple yet great app for those out there pushing pills. 3 stars because it has some bugs that need fixing now. Updated my phone to iOS 10 and now this app crashes if 2 or more fields have a period in it. Will fix review to 5 stars once bugs are removed. ### 1/5 — Way off *2016-01-22, version 3.0* This app has been confusing me. I have this and one other gamma ray app along with the old school exposure calculator that companies give you. Shooting a 42" panoramic, it says I should shoot it 1min 35secs. Which is what I shoot a 36" panoramic with the same cuties. At a 4 minute develop time for the 36", it's perfect density. The other app I have says 2 min 10sec which sounds more accurate. Think I'll be using my other app instead of this one. ### 4/5 — Use it all day.. *2015-06-18, version 3.0* Need an update already, like which wire to use, maybe with the coundown it shows the density climbing up and uou can stop it at your desired density...ect. Love the app. Looking forward to see whatsnext ## Frequently asked questions about X ### What does this app do? This application is designed to calculate radiography shot times for industrial radiographers. It replaces the need for traditional slide rules by providing a quick and efficient digital solution for determining exposure times. ### What are the key features of this app? The app allows users to input the number of curies, the thickness of steel in inches, and the source-to-film distance in inches. It then calculates the necessary exposure time. It is specifically designed for use with Iridium and Cobalt radioactive sources. ### Is this app free to use? Based on the provided information, this application is a paid app. There are no mentions of in-app purchases or advertisements, indicating a one-time purchase model. ### What type of radiography does this app support? This app is exclusively for industrial radiographers working with radioactive materials, not x-ray machines. It supports both Iridium and Cobalt sources for these specific applications. ### Who is the target audience for this app? The app is intended for industrial radiographers who work with radioactive materials. It has been field-tested with working radiography crews and received positive feedback, suggesting its utility in real-world industrial settings. ## Version history (last 5 releases) ### 4.0 — 2016-09-30 This app has been updated by Apple to display the Apple Watch app icon. Fixed crashing issue in iOS 10. ### 3.0 — 2012-07-18 Added metric units. Updated for Retina graphics. Performance improvements. ### 2.1 — 2010-10-09 Changed the default keyboard to a numeric keyboard. Saves a step when entering data. ### 2.0 — 2010-06-24 Added Se-75 as an Isotope option. Based on values provided by manufacturer, I don't own a Se-75 source. ### 1.0 — 2010-01-14 No release notes. ## Apps similar to X | App | Rating | Price | Category | | --- | --- | --- | --- | | [Arc Calculator Pro](https://appshunter.io/ios/app/arc-calculator-pro/id1491369908) | — | $3.99 | Utilities | | [GammaGadget](https://appshunter.io/ios/app/gammagadget/id6639622489) | — | $4.99 | Utilities | | [HeavyCalc Pro](https://appshunter.io/ios/app/heavycalc-pro/id390275254) | 3.0 (5) | $39.99 | Utilities | | [WRAP-Iowa Ramp Design Aid](https://appshunter.io/ios/app/wrap-iowa-ramp-design-aid/id1512276816) | 5.0 (1) | Free | Utilities | | [Moments of Inertia](https://appshunter.io/ios/app/moments-of-inertia/id494181506) | 1.0 (1) | $5.99 | Utilities | | [Equal Space](https://appshunter.io/ios/app/equal-space/id6743153922) | — | $0.99 | Utilities | ## More apps by Lance Henderson - [Barricade](https://appshunter.io/ios/app/barricade/id348247916) - [Ug Calc](https://appshunter.io/ios/app/ug-calc/id436130906) - [Density](https://appshunter.io/ios/app/density/id458423388) All apps by Lance Henderson: https://appshunter.io/developer/348247919 ## Related topics [xray timer](https://appshunter.io/ios/topics/xray-timer) --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-17.*